Workshop
Vineyard Hotel, Cape Town
3 August 2011
Effluent treatment for values recovery
and mitigation of environmental impact
Solid and liquid effluents from minerals processing and extractive metallurgical processes invariably contain constituents that can represent both threats to the environment if left untreated and opportunities if recovered as commodities. Environmental impact is effected by the slow but continuous release of heavy metals and acid drainage into natural waterways, often well beyond the operational life of a particular industrial activity. This necessitates continuous monitoring and ongoing mitigation. At the heart of this release are aqueous chemical (i.e. hydrometallurgical) processes such as oxidation, dissolution and complexation, often supported by the activity of micro-organisms. At the same time, most treatment processes also rely on selected hydrometallurgical or bio-hydrometallurgical processes. Less well explored, but of increasing importance, are processes that actively target the selective recovery of metals, salts and acid to generate revenue to subsidise treatment, if not even turn a profit.
This workshop aims at giving participants a comprehensive introduction to the field of effluent treatment. The first part covers the fundamental hydrometallurgical processes and aqueous chemistry at the heart of both environmental release as well as treatment and recovery processes. This session will be delivered by Prof. Mike Nicol, formerly Mintek, Wits and Murdoch University, who is recognised as the leading expert in the science of hydrometallurgy. In the second part, sessions will be delivered by Prof Alison Lewis, Dr Rob van Hille and Dr Jochen Petersen, from UCT, to cover processes employed or under development for the treatment of and/or recovery from wastes in the minerals industry. These include: precipitation of stable solid residues, bio-remediation of acid mine drainage, recovery of low grade acid or sulphur from sulfide wastes, selective adsorption of valuable metals from waste water streams, matching acid with alkaline waste streams, desalination, etc. A final presentation will make the business case for such technologies.
Workshop participants should come away having a sense that many relatively mature technologies for the meaningful integration of waste processing into primary metallurgical processing exist, and that these and should no longer be seen as a costly add-on to primary business, but as a business opportunity for additional value generation.
